In the prior holiday lights, a number of small low-voltage bulbs connected in series are lit up simultaneously. Due to the serial connection, a blown fuse or the removal of one or more of the bulbs will interrupt the complete series circuit connection. To solve this problem, China Patent CN2253524Y discloses a bulb with a resistance wire that can complete the circuit when the bulb's tungsten filament is fused, so as not to affect normal operation of other bulbs. However, according to the technology disclosed in the China Patent CN2253524Y, the resistance wire or fuse is disposed within the bulb, so when one bulb in a decorative light string consisting of such bulbs comes off, an open circuit will still occur, causing the entire string of bulbs to go out.